Arc lamp



March 6, 1934. p 1,949,687

ARC LAMP Filed June 20, 1929 INVENTOR BY WiWv, ATTORNEYS Patented Mar. 6, 1934 UNITED STATES PATENT OFFICE ARC LAIWP of New York Application June 20, 1929, Serial No. 372,478

4 Claims.

This invention relates to electric arc lamps and in particular to improvements in the automatic control mechanism for operating such lamps.

In the usual form of arc lamps the electrodes are normally in contact when the arc is not burning and there is no current on the lamp. As the current is turned on the electrodes are caused to separate by the action of a solenoid connected in series with the electrodes. The solenoid must be of such power that, on being energized, it will not only separate the electrodes to draw an are but will support them continually while the arc is burning. As the arc becomes longer and the voltage across the arc increases, the current through the solenoid is weakened causing it to release the electrodes and allow them to feed.

In lamps burning two or more arcs this means of control often results in very unsatisfactory burning conditions due to the fact that the elec- 2 trodes do not feed evenly, giving arcs of unequal length and in many instances causing one pair of electrodes to be entirely shorted by remaining in contact. The power lost in supporting the electrodes and other moving parts is considerable and zsheating of the solenoid is usually encountered.

When using alternating current different resistance adjustments must be provided for difii erent frequencies and a constant vibration in the'solenoid causes objectionable noise.

In accordance with my invention these and other disadvantages of the old solenoid feed arrangement are entirely eliminated and an improved operating mechanism is provided which may be adapted to any type of arc lamp. One of the objects of this invention is to provide an arc lamp which will be universal in its operation and will operate equally well on alternating current of any frequency or on direct current.

Another object is to provide a control mecha- 40 nism which does not heat up and which will operate quietly on alternating current.

Another object is to provide a lamp which will give much better burning characteristics especially when using multiple arcs.

These and other objects of my invention will be evident from a description of the accompanying drawing showing one embodiment thereof, wherein Figure 1 is a side elevation of one type of control mechanism.

Figure 2 is a front view of the same mechanism.

Figure 3 is a diagrammatic sketch of a suitable electrical circuit.

As shown the invention is adapted to a twin arc lamp burning two arcs in series between the carbon electrodes 10. The lower electrode holders 11 are stationary while the upper holders 12 are free to move vertically on the guide shafts 13. Clutches 14 are adapted when raised to grip the upper carbons and raise them thus separating 1 the electrodes. These clutches are connected by means of a drop link 15 and a cross piece 16 to a channel shaped rocker shaft 17 mounted in the supports 18. This rocker shaft may be revolved about its points of support to raise or lower the clutches l4.

Rigidly attached to one end of the rocker shaft, better shown in Figure 1, is a lever arm 19 which is normally held in a raised position by means of a spring 20. In this position the clutches 14 are always raised and the electrodes separated. A high resistance solenoid 21, shown in Figure 1 as two individual solenoids connected in series, has an armature 22 which is attached to the lever arm 19 by means of an adjustable rod 23. Mounted below the solenoid 21 is a relay coil 24 provided with an armature 26 adapted to make and break an electrical circuit. The entire mechanism may be mounted in any suitable manner. As shown three horizontal support members 27 are provided which are tied together by a vertical center rod 28. The vertical support 29 is used as a mounting for the solenoid and relay. Additional support for the horizontal members may be provided in the lamp housing which is not shown here and forms no part of the present invention.

The wiring diagram of Figure 3 shows the preferred electrical circuit, in which the relay coil 24 is in series with the arcs and the solenoid 21 is shunted around both the arcs and the relay. When contact has been made between the elec trodes 10 and the arcs are burning the circuit 30 is complete, the relay coil 24 has been energized, the armature 26 has been raised to the position shown, and the shunt circuit 31 through the solenoid 21 has been disconnected. The armature 26 completes the shunt circuit 31 when the relay coil 24 is not energized or, in other words, whenever there is no current flowing between the electrodes.

When starting the arc the electrodes will normally be separated being held in that position by the force of the spring 20. With the electrodes in this position the circuit 30 is broken so that when electrical contact is made to the lamp from an outside source, the current will first flow through the shunt circuit 31 and energize the solenoid 21. This exerts a pull on the armature 22, lowers the lever arm 19 against the action of the spring 20, and in turn lowers the clutches 14, thus releasing the electrodes 10. As the electrodes touch, the circuit 30 is completed and the relay coil 24 becomes energized raising the armature 26 and breaking the shunt circuit 31. The solenoid 21 is thus de-energized and the spring is again allowed to act, causing the clutches 14 to raise and separate the electrodes to form the arcs. It is evident that the high resistance solenoid 21 is now out of circuit and it will remain so as long as the arc is burning and the relay coil 24 is energized. As the carbon electrodes burn away the length of the arcs gradually increases until they finally break. When this happens the flow of current through the relay coil is interrupted, the armature 26 drops down, completes the shunt circuit 31 and again causes the solenoid 21 to be energized. A repetition of the previous operation now takes place and the cycle continues to repeat as long as cur rent is applied to the lamp circuit.

If by any chance the electrodes should be in contact instead of separated when current is first turned on the lamp it would appear from the explanation as given that the relay coil 24 would be energized immediately, causing the circuit through the solenoid 21 to be broken before said solenoid could be energized and act to lower the clutches 14. In such an event the carbon electrodes would remain in contact, the circuit through the relay would be shorted, the solenoid would be out of circuit, preventing the drawing of an arc. To insure the correct operation of the solenoid and relay in their proper sequence a dash pot 32 may be attached to the armature 26 and so arranged that it will delay the breaking of the solenoid circuit until said solenoid has had time to act and lower the clutches. The delay necessary is so short that it will in no Way aifect the proper operation of the arcs after they have been once started.

Various modifications in the mechanical arrangement as shown may easily be made without departing from the spirit of my invention. A weight may be hung from the opposite end of the lever arm 19 which would act in the same manner as the spring 20, in conjunction there with or alone, to keep the arm normally in a position which will raise the clutches 14. The dash pot 32 may be replaced by a number of means for insuring operating of the relay and solenoid in the proper sequence. An interlocking device may be provided between the armatures 22 and 26 arranged with a latch so that the armature 26 cannot operate to break the contact until the latch has been tripped by operation of the armature 22. Other delay mechanism such as a mercury switch, an escapement, or a switch with a wiping contact attached to the armature 26 may also be suitable for this purpose.

An arc lamp with a control mechanism as described will operate equally well on alternating current of 25 or cycles, or on direct current. The same resistance unit will serve for any frequenoy and will require adjustment only in the case of a wide change in line voltage. When burning two or more arcs the length of each will always be the same giving much more uniform burning characteristics. Since the high resistance solenoid is always out of circuit while the arc is burning there is no heating the lamp from this source and the characteristic solenoid hum and vibration obtained with alternating current is absent. The low resistance relay coil develops no noticeable heat or noise.

My invention as described has been applied to a twin arc lamp, but it is evident that it may be equally useful with a single or multiple arc lamp.

I claim:

1. In an operating mechanism for an arc lamp, means adapted to normally maintain a pair of electrodes in separated position, means including a solenoid in shunt circuit with the arc operative when energized to release said electrodes and permit them to contact by gravity, a relay in series circuit with the arc operative to make and break the solenoid circuit, and means associated with the circuit breaker of said relay to delay its action.

2. An operating mechanism for an arc lamp comprising a clutch adapted when raised to lift an electrode, means normally holding said clutch in a position, a solenoid in shunt circuit with the arc and operative when energized to lower said clutch, relay in series circuit with the arc and operative when energized to break the solenoid circuit, and means delaying operation of the relay circuit breaker until the solenoid is energized.

3. An arc lamp comprising upper and lower e eotrodes, clutches adapted to be raised and lowered to lift the upper electrodes, a rocker shaft and lever arm operatively connected to clutches, means attached to said lever arm to normally hold the clutches in a raised position, a solenoid operatively connected to said lever arm and adapted when energized to lower said clutches, a relay, a series circuit including said electrodes and the coil of said relay, a second circuit in shunt with electrodes including the solenoid and the circuit breaker of said relay and a dashpot operatively connected with the relay circuit breaker to delay its action.

4. An arc lamp comprising stationary lower electrodes and movable upper electrodes, clutches adapted to be raised and lowered to lift the upper electrodes, a rocker shaft and lever arm operatively connected to said clutches, means including a spring attached to said lever arm normally holding the clutches in a raised position, a solenoid in shunt circuit with the arcs opera.- tively connected to said lever arm and adapted when energized to lower said clutches, a. relay in series circuit with the arcs and operative when energized to break the solenoid circuit, and means delaying the operation of the relay circuit breaker until the solenoid is energized.

HENRY E. KIP. 

